This invention relates to a method of controlling a fluid in a life support system including at least one of a G-suit and a counterpressure garment e.g. for a member of an aircrew of a high performance aircraft.
Description of the Prior Art
It is common practice in a control system to sense the effect of operating a control effector such as a valve, in order to use feedback, so that the control effector may dynamically be adjusted in order that the actual parameter being controlled e.g. fluid pressure or flow, may be brought to a desired value. Thus control of the parameter is achieved purely in response to the effect of operating the effector. Such control is insufficiently refined for many applications and there is the possibility of the actual parameter being controlled not remaining within acceptable limits.
It is also known to measure e.g. using a transducer, the position of a moveable part of a valve, such as a valve stem, in response to a control input, to monitor and control the valve operation incrementally in response to a control signal, in an effort to keep the actual parameter being controlled within acceptable limits. However physically measuring position and making the necessary calculations is too slow for application to a high performance life support system.